Some characters are nonprintable.
A nonprintable character is a character for which there is no visible image,
such as backspace or a control character. Other characters have special meaning
in the language, such as the single and double quotation marks, and the
backslash. Nonprintable characters and special characters are written using an escape
sequence. An escape sequence begins with a backslash. The language
defines the following escape sequences:

newline

\n

horizontal tab

\t

vertical tab

\v

backspace

\b

carriage return

\r

formfeed

\f

alert (bell)

\a

backslash

\\

question mark

\?

single quote

\'

double quote

\"

We can write any character as a generalized escape sequence
of the form

\ooo

where ooo represents a sequence of as many as three
octal digits. The value of the octal digits represents the numerical value of
the character. The following examples are representations of literal constants
using the ASCII character set:

\7 (bell) \12 (newline) \40 (blank)
\0 (null) \062 ('2') \115 ('M')

The character represented by '\0' is often called a
"null character," and has special significance, as we shall soon see.